Membrane fusion is a fundamental process supporting a life and performed by proteins specific to each occasion. Some peptides related to fusion-inducing domain of these proteins could induce the fusion with a formation of alpha-helix which is necessary but not a sufficient condition for the process. However, a detailed picture of the fusion, the dynamics of fusion-inducing alpha-helix in membranes, has not yet been established. From our preceding studies, peptide a-helix orientation in membranes was indistinguishable between active and inactive states. For other possibility, peptide association in membranes was considered and tested in the present study. Since we have no general method to study molecular association in membranes, we chose fluorescence energy transfer as a method to evaluate the intermolecular distance. General approach to use bulky and strongly hydrophobic fluorescent probes, which possibly perturb the structure of peptide itself, was avoided. We tried probes having th
… Moree structure as possible as close to parent amino acids, and 3-nitrotyrosine was the choice. In this case a nitro group in 3-nitrotyrosine quenched transferred energy efficiently and donor fluorescence might disappear. Formation of a specific secondary structure, association and dissociation of various peptides in aqueous media, also in membranes, were successfully detected with a use of tryptophan as a fluorescence energy donor (emission maximum at 350 nm) and 3-nitrotyrosine as an acceptor (absorption maximum at 360 nm). But the result in membranes showed that the change of association state of membrane fusion-active peptides was minimal under active and inactive conditions. These findings requires that no drastic change in peptide association mode is followed in induction of the fusion and other factors of lipid-peptide interactions must be sought.We were constructing a reference database for lipid-membrane interactions which was expanded to include nearly 3000 references, as one of activity in the present study.3. 生体膜とタンパク質の相互作用に関する文献データベースを以前から作り始めていたが、現在約3000文献を集めたものが出来た. Less